Thermodynamic simulation and mathematical model for single and double flash cycles of Cerro Prieto geothermal power plants

Abstract

Geothermal power generation technologies are well established and there are numerous power plants operating worldwide. The Cerro Prieto geothermal field is located in northwestern Mexico, approximately 32 km from the US-México border. A single flash and double flash cycle have been selected for power generation. The study is aimed to thermodynamic simulation and mathematical model development for the single and double flash cycles. Thermodynamic Simulation for energy flows were developed and implemented in Aspen Hysys software, while the multiple linear regression analysis was developed in IBM SPSS software. The single flash cycle thermodynamic simulation of the proposed design shows the plant’s maximum net power output can reach 36.667 MW if the separator and condenser pressures are 650 kPa and 11.5 kPa, respectively. In the double flash cycle, the optimum pressure value for high pressure (HP) separation is 1200 kPa, low pressure (LP) separation is 385 kPa and the pressure for condenser was determined to be 11.5 kPa, the maximum net power output of the plant is 102.112 MW. The multiple linear regression shows mathematical model to predict the net power and thermal efficiency for single flash and double flash cycles, using the independent variables of the well temperature, separator pressure and condenser pressure to obtain a mathematical expression that predicts the behavior of this cycle. While for the double flash cycles, the well temperature, the pressures in the separators and the condenser pressure are used. The mathematical models to predict the net power and the thermal efficiency of the cycles shows a very good approximation to the thermodynamic analysis, the single flash cycle shows ANOVA results net power (r=0.999885, R2=0.999769, p<0.0001) and thermal efficiency (r=0.999628, R2=0.999256, p<0.0001), while the double flash cycle ANOVA results net power (r=0.999861, R2=0.999722, p<0.0001) and thermal efficiency (r=0.999806, R2=0.999612, p<0.0001).